1. Field of the Invention
This invention relates to a gun arm apparatus used chiefly for a portable type resistance welding gun.
2. Description of the Prior Art
In prior art portable resistance welding guns, the gun arm main body has at its front end portion an electrode holder and at its rear end portion a supporting member. A conductor connects the electrode holder to a source of electric power. Additionally, a water passage means is provided in the main body for cooling.
Japanese Utility Model Application Publication No. Sho 57-24455 discloses a gun arm in which the main body is formed of a tubular body made of a comparatively thin plate, and a copper pipe is provided therein which functions as both the conductor and the water passage means. This arrangement, however, is inconvenient in that it is difficult to make a copper pipe with a sufficient electric current capacity, and the gun arm apparatus becomes comparatively large in cross-sectional area because of the fact that the main body is tubular in form. Additionally, the gun arm becomes complicated in construction and difficult to manufacture.